This invention relates to a power control system and method for supplying power to a system to which a plurality of devices are connected.
A printer generally is connected to a personal computer serving as a host device via a Centronics interface for parallel data transmission or RS-232C interface for serial data transmission.
Items of digital equipment serving as image display devices such as scanners, digital still cameras and digital video cameras may also be connected to a personal computer. The image data input by each item of digital equipment is temporarily loaded onto a hard disk or the like of the personal computer and is subsequently converted to print data for the printer by being processed as by application software running on the personal computer. The print data is sent to the printer via the above-mentioned interface.
The widespread use of digital equipment such as digital cameras has been accompanied by the development of techniques that make it possible to handle this digital equipment more conveniently. One example of such a known technique is to directly connect a digital camera and printer together and output the image captured by the digital camera to the printer directly. In accordance with this technique, an image captured by the digital camera can be printed out without the intervention of a personal computer.
Accordingly, the use of digital equipment, a prime example of which is the digital camera, is fostered even among users who do not possess a personal computer.
In a system that implements direct output of this kind (referred to as a xe2x80x9cdirect printing systemxe2x80x9d), connecting an editor to the system instead of a personal computer makes it possible edit and combine images through a simple operation.
In such a direct printing system, electric power is supplied to the devices (digital camera, printer, etc.) that construct the system. In general, 100V AC power supplied by a power company is used as the power source.
In domestic indoor wiring, the peak supplied power is controlled by the breaker of a power board. A power board usually has a two-stage construction, namely a breaker of a main power source and breakers for respective ones of a plurality of power channels. The breaker of each power channel limits the usable current in accordance with the current rating of the wiring, and the breaker of the main power source limits the maximum current, which is based upon an agreement with the power company.
Accordingly, each device constituting the direct printing system is connected to an AC power source supplied via a breaker, as a result of which stabilized supply of power is assured at all times.
In the example of the prior art described above, however, an AC adapter connected to the AC power source to supply power is required to be connected to each of the connected devices, namely to the digital camera, editor and printer. Cables serving as signal lines connecting the devices together so that data may be transferred among them also are necessary. Consequently, the operation for making the connections to construct the system is troublesome and complicated.
In addition, a plurality of connectors for the AC adapters and signal lines are required for both the digital camera and editor. Thus, the prior art involves a number of problems not only in terms of user convenience but also in regard to the space required for the connectors of each device and the cost of making the connections.
Further, in regard to the breaker that limits the peak of ordinary AC power, whether or not to break the current path is a decision made based upon the amount of current that actually flows through the wiring. Consequently, it is required that each of the terminal devices (inclusive of the digital camera and printer, etc.) that actually use the supplied power be controlled individually by the user in such a manner that the above-mentioned limitation is satisfied. In other words, in order that the breaker will not interrupt the supply of power to the corresponding power channel, the amount of power presently being used must be adjusted manually as by turning on and off the power sources (i.e., the power switches) of household appliances, etc., being used in this power channel.
A method that has been considered in order to maintain the supply of power without limiting the use of the terminal devices involves updating the agreement with the power company for the contracted current in conformity with the peak current used. However, this is undesirable in view of economy and conservation.of power.
In particular, though average power consumption tends to decrease as electrical appliances that employ inverter techniques increase, the increase in peak current is conspicuous. More specifically, increasing the contracted current in order to assure peak current for very short periods of time or compelling the user to connect terminal devices to the power sources of separate channels detracts greatly from economy and user convenience.
Further, owing to the increased number of functions with which modern electrical appliances are provided, there tend to be more items (time, etc.) that need to be initially set at the time of installation. Since even standby power supplied to each device is interrupted by the tripping of a breaker, it is necessary for the user to make the initial setting of each device again when such an interruption occurs. In addition, depending upon how the terminal devices, which are not limited to digital cameras and printers but can also include medical equipment, are being used, the effects of an interruption in the supply of power can be serious.
Furthermore, since equipment for supplying power must be provided to deal with peak currents that last for very short periods of time, an increase in such peak current is accompanied by the necessity to provide more of such equipment. This not only leads to much higher cost but also lowers energy efficiency when power is generated. The latter is attended by deleterious consequences for the environment.
Accordingly, it is an object of the present invention to provide a power control system and method through which the signal-line connector of each of a plurality of devices connected into a system can be integrated with the power-supply connector of the device to make possible the use of a single, common cable.
According to the present invention, the foregoing object is attained by providing a power control system to which a plurality of devices are connected by connecting means for transferring data and supplying power, comprising: power-source connecting means for connecting a prescribed device among the plurality of devices to a power source; and power control means for supplying power from the prescribed device to the other devices, which are connected via the connecting means, in accordance with a power distribution that is based upon power information in the plurality of devices.
As a result, it is easier to connect devices together and it becomes possible to reduce the space required for the connectors of the devices as well as the cost of making the connections.
It is another object of the present invention to provide a power control system and method through which effective distribution of power is performed among a plurality of devices by dynamically controlling the supply of power on a line.
According to the present invention, the foregoing object is attained by providing a power control system for supplying power to a plurality of devices interconnected on a power source line, comprising: distribution deciding means for deciding distribution of power to each of the plurality of devices based upon power information in each device; and mode control means for controlling a power consumption mode of each device in accordance with the distribution of power decided by the distribution deciding means.
As a result, it is possible to distribute power effectively among a plurality of devices.
The invention is particularly advantageous since devices can be connected together more easily, connector space for each device can be reduced and costs can be lowered through use of a common cable achieved by integrating the signal-line connector of each of the devices with the power-supply connector of each device.
Further, effective distribution of power is performed among a plurality of devices by dynamically controlling the supply of power on a line.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.